If you head north from Disneyland on Harbor, you get to the corner of Harbor and Orangethorpe in about 3 miles. This area has lots of shops, including a Super Walmart, a Target, a COSTCO (need a membership) Market, a Disney Parks Outlet Store (DIsney's Character Warehouse), a Sketchers Outlet Shoe Store, plenty of places to eat, like In-n-Out Burger and much more.
To get there without a car is easy, OCTA Route 43 runs up and own Harbor Blvd much of the day in about 15 minute intervals. So maybe the bus up ($1.50 per adult one way) and then a taxi back to bring your shopping back to the Hotel.
FYI, Walmart would more than likely have slightly lower prices than Target.
www.octa.net